Sealing Arrangement Having A Rod Seal, Output Apparatus For Discharging A Flowable Medium And Rod Seal

ABSTRACT

A sealing arrangement having a rod seal for sealing a cavity for a flowable medium in the region of a rod includes an output apparatus for discharging the flowable medium. The rod is movably supported in a housing to be displaced in an axial direction. The housing has a bearing portion, wherein the rod seal is supported in a fixed manner and wherein the rod extends through the bearing portion and the rod seal so that a first rod portion and a second rod portion are arranged at different sides of the bearing portion. The first rod portion is located at a side facing the cavity and the second rod portion is located at a side facing away from the cavity. The rod seal is arranged at the side of the bearing portion facing the first rod portion and has a first sealing lip and a second sealing lip that are spaced apart from each other in the axial direction and circumferentially contact the rod. The bearing portion facing the cavity has a discharge structure having a support face which circumferentially surrounds the rod. The rod seal is in abutment with the support face and the support face has a diameter which increases in the direction of the second rod portion.

FIELD OF THE INVENTION

The present invention relates to a sealing arrangement having a rod sealfor sealing a cavity for a flowable medium in the region of a rod. Inaddition, the invention relates to an output apparatus for discharging aflowable medium, in particular an output apparatus for discharging anadhesive. Furthermore, the present invention relates to a rod seal. Theflowable medium is preferably a hot adhesive or a melt adhesive. Theoutput apparatus is in particular an application head, in particular aninjection head or spray head or coating head.

Sealing arrangements having a rod seal are used in particular in sectorsin which a region of a housing which contains a flowable medium isintended to be sealed in the region of a rod which can be moved relativeto the housing. In rods which carry out a rotating movement, if they areconstructed as a shaft, so-called radial shaft sealing rings are oftenused. The rod may, however, also be a rod which carries out atranslational movement, such as, for example, a piston rod of a pistonpump or a valve rod.

DE 10 2013 212 961 A1 discloses a rod seal in the form of a radial shaftsealing ring, wherein this radial shaft sealing ring is used to sealrotating shafts when they pass from an inner space of a housing into anouter space. The inner space typically contains in this instance a fluidor a lubricant, such as, for example, engine oil in radial shaft sealingrings which seal a crankshaft of a motor vehicle.

In the sector of radial shaft sealing rings, the use of dual lip sealingrings is known, wherein the radial shaft sealing ring has sealing lipswhich are formed to be spaced apart from each other in an axialdirection and which contact the rod circumferentially, wherein the firstsealing lip serves to actually seal the inner space with respect to theouter space and the other sealing lip acts as a dust protection. DE 2348 868A discloses such a shaft seal.

For the purposes of sealing translationally movable rods, in principlesealing arrangements can be used in which the rod seal is supported in afixed manner in the housing and the rod moves relative to a sealingportion of the rod seal, for example, a sealing lip of the rod sealwhich circumferentially abuts the rod. A disadvantage of this type ofseal is that, over a long period of operation, the sealing portionbecomes worn and as a result the sealing can lose its sealing effect,whereby undesirable discharge of flowable material from the cavity inthe region of the rod can occur. In addition, it has been found that thereliable function of the sealing arrangement is highly dependent on thepressure and temperature of the medium located in the cavity.

A particular challenge for the sealing arrangement are temperaturecycles. During the heating of a solid medium in order to make itflowable, as a result of material expansions local pressure peaks whichmay be a multiple of the pressure loading during operation may occur.

This particularly occurs when only a portion of the medium is liquefiedand the remainder is still solid. Conventional sealing arrangements canthereby be slightly damaged. During the cooling, as a result ofdifferent material contractions, particularly caused by the transitionof the medium from the liquid state into the solid state, additionalloads on the sealing arrangement may be caused.

Translationally movable rods are used, for example, in outputapparatuses, for example, in the form of application heads. Such outputapparatuses are used, for example, to apply flowable medium in portionsto a substrate. The application of the flowable medium is in thisinstance generally carried out in a controlled manner, wherein theapparatus has an output opening for discharging the flowable medium,wherein this output opening can be closed and opened by means of asealing portion of a rod which can be moved with an actuator. Such anoutput apparatus thus has a closable valve.

With regard to such an output apparatus for discharging flowable medium,the problem involves sealing a region which contains the flowable mediumin the region of the rod, in particular in order to prevent the flowablemedium from reaching the region of an actuator or the drive which drivesthe rod. Between the cavity and the drive there is normally anintermediate space which is sealed at the side of the cavity and at theside of the drive. The sealing arrangement should also prevent themedium from reaching this intermediate space. If medium does reach thisintermediate space, it is an indication that the sealing arrangement isworn. The valve can then be operated further for a limited time with theidentifiable leakage. If the medium were to reach the drive directly,the drive would then become clogged in a short space of time andnon-operational.

In the sealing arrangement according to the invention, a rod seal havingat least two sealing lips is used in order to achieve a particularlygood sealing action. The use of at least two sealing lips is consideredto be advantageous in that, with an output apparatus for discharging aflowable medium, the flowable medium generally has a higher pressurecompared with the environment. Generally, the flowable medium has anoperating pressure of from 10 bar to 100 bar above ambient pressurewhich is generally approximately 1 bar. The first sealing lip whichfaces the flowable medium serves to seal with respect to the pressure ofthe medium. The first sealing lip may have a slight leak. The secondsealing lip wipes this leak of the first sealing lip from the rod.

When a seal having two sealing lips is used, it has been found to beproblematic that the pressing force of the two sealing lips on the rodis highly dependent on the pressure of the flowable medium which isintended to be sealed. The wear of the sealing lips becomes greater, thegreater the pressure of the medium. It has additionally been found to beproblematic that the distribution of the pressing forces of the twosealing lips is highly dependent on the pressure of the medium which isintended to be sealed. The sealing action becomes worse, the more thesepressing forces differ. This results in the problem that the sealingaction of the seal is not leak-free over the entire pressure,temperature and viscosity range. At a particularly low operatingpressure of the flowable medium, for example, the pressing forces of thesealing lips are too low on the rod to ensure a reliable andleakage-free sealing.

In addition, in conventional dual lip seals there is the problem thatthey are generally constructed for a narrow field of use, that is tosay, for a narrow pressure range, and therefore cannot be useduniversally. This results in a sealing arrangement having a conventionalconfiguration and arrangement of the dual lip seal with regard to theoperating pressure of the flowable medium being limited to a narrowrange. If this narrow pressure range is left for higher pressures, thepressing forces on the sealing lips become too great with the resultthat the wear of the sealing lips is too great and the service-life isshort. Temperature cycles in the form of heating and cooling withexcessively high pressures also reduce the service-life of the sealingarrangement. If the narrow pressure range is left for lower pressures,the pressing forces on the sealing lips become too small so that a leakoccurs.

Objects of the Invention

An object of the present invention is therefore to provide a sealingarrangement having a rod seal which overcomes the above-mentioneddisadvantages, in particular a sealing arrangement which over a largepressure range achieves a reliable sealing action with low wear of therod seal nonetheless. An object of invention is further to provide anoutput apparatus which serves to discharge the flowable medium havingsuch a sealing arrangement. In addition, an object of the invention isto provide a corresponding rod seal. Preferably, the sealing arrangementshould be suitable for exceptionally high cycle rates in the range of500 million strokes and the service-life of the seal should be extremelyhigh under the specific conditions of use.

These objects are achieved by a sealing arrangement which has thefeatures of the present invention, an output apparatus which has thefeatures of the present invention and a rod seal which has the featuresof the present invention.

SUMMARY OF THE INVENTION

The sealing arrangement according to the invention serves to seal acavity which is formed in a housing in the region of a rod. The cavityserves to receive a flowable medium. The rod is supported in the housingso as to be able to be moved, preferably displaced, in an axialdirection of the rod, in this regard in a translational manner. Thehousing has a bearing portion and a rod seal which is supported in afixed manner in the bearing portion, wherein the rod extends through thebearing portion and the rod seal so that a first rod portion of the rodand a second rod portion of the rod are arranged at different sides ofthe bearing portion, wherein the first rod portion is located at a sideof the bearing portion facing the cavity and wherein the second rodportion is arranged at a side of the bearing portion facing away fromthe cavity. The rod seal is arranged at the side of the bearing portionfacing the cavity. The rod seal has at least a first sealing lip and asecond sealing lip, wherein the sealing lips are spaced apart from eachother in the axial direction and circumferentially contact the rod. Thebearing portion has at the side thereof facing the cavity a dischargestructure having a support face which circumferentially surrounds therod for the rod seal, wherein the rod seal is in abutment with thesupport face. The support face has a diameter which increases in thedirection of the second rod portion.

As a result of the fact that the support face has a diameter whichincreases in the direction of the second rod portion, the support faceis configured in such a manner that it tapers in the direction of thecavity or the first rod portion, whereby forces which act on the supportface in the direction of the second rod portion can be dischargedradially outwards. This has the advantage that, as a result of thepressurised medium, forces acting on the rod seal are dischargedradially outwards so that, as the pressure of the flowable mediumincreases, the resultant forces on the rod seal are at least partiallydischarged radially outwards so that a pressing force of the sealinglips, in particular the second sealing lip, on the rod increases to alesser extent than would be the case if it were a planar support face orif the support face were to even have a diameter which decreases in thedirection of the second rod portion and thus would have a funnel-likeshape. It has been found that, as a result of this configuration of thesupport face, a pressing force of the sealing lips on the rod can bekept substantially constant over a large pressure range of the flowablemedium and in addition a ratio of the pressing force of the firstsealing lip with respect to the pressing force of the second sealing lipremains substantially constant over a large pressure range of theflowable medium. In addition, the sealing arrangement according to theinvention has also been found to be advantageous with regard to the mostconsistent possible pressing force even when the sealing lips becomeworn.

The flowable medium preferably has a temperature of from about 50° C. toabout 250° C., preferably from about 100° C. to about 200° C. Theoperating pressure of the medium is preferably from about 10 bar toabout 100 bar above the ambient pressure which is generallyapproximately 1 bar. The medium is preferably a viscous fluid. Theviscosity of the flowable medium is preferably from about 0.1Pascal-second (Pa-s) to about 100 Pa-s, preferably from about 0.5 Pa-sto about 10 Pa-s.

The flowable medium is preferably in particular a melt adhesive.However, it may also absolutely be a cold glue. The flowable medium mayfurther also be a sealing agent or a lubricant.

The rod of the sealing arrangement is preferably a piston rod or a valverod.

The sealing arrangement is preferably a component of a conveyingapparatus for conveying the flowable medium. The conveyor device ispreferably a piston pump, wherein the rod is the piston rod, wherein theflowable medium is conveyed by means of the displacement of the pistonrod.

The sealing arrangement is preferably a component of an output apparatusfor discharging the flowable medium. The output apparatus is preferablya metering valve of an application head.

The sealing arrangement may absolutely be a component of a valve, inparticular an excess pressure valve.

The displacement of the rod is preferably carried out by means of adrive which is operationally connected to the rod, in particular to thesecond rod portion.

The output apparatus according to the invention serves to discharge theflowable medium. The output apparatus has the sealing arrangementaccording to the invention, wherein the output apparatus has a dischargeopening which opens in the cavity for discharging the flowable medium inthe cavity from the cavity, for example, in order to apply the medium toa substrate, wherein the rod is supported in the housing so as to beable to be moved between a first end position and a second end positionin the axial direction, and vice versa, wherein the rod has a sealingportion, wherein the sealing portion closes the discharge opening in thefirst end position and is arranged in the second end position withspacing from the discharge opening so that flowable medium can bedischarged from the discharge opening, wherein the discharge opening hasa drive, wherein the drive is operationally connected to the rod, inparticular to the second rod portion of the rod, in order to move therod from the first end position into the second end position, and viceversa. The drive may, for example, be a pneumatic cylinder or hydrauliccylinder, wherein a piston or a piston rod of the pneumatic cylinder orhydraulic cylinder is connected to the rod. The rod may absolutely formthe piston rod of the pneumatic cylinder or hydraulic cylinder.

The output apparatus according to the invention for discharging aflowable medium is in particular an output apparatus for discharging anadhesive, preferably for discharging a melt adhesive.

The flowable medium preferably has a temperature of from about 50° C. toabout 250° C., preferably from about 100° C. to about 200° C. Theoperating pressure of the medium is preferably from about 10 bar toabout 100 bar above ambient pressure, which is generally 1 bar. Theviscosity of the flowable medium is preferably from about 0.1 Pa-s toabout 100 Pa-s, preferably from about 0.5 Pa-s to about 10 Pa-s.

The output apparatus for discharging a flowable medium is in particularconstructed to discharge the flowable medium in an intermittent manner.A switching frequency of the output apparatus is preferably up to about150 Hz, in particular with a switching frequency of from about 1 Hz upto about 150 Hz.

The output apparatus is in particular in the form of a meteringapparatus.

It is further considered to be particularly advantageous for thediameter of the support face to continuously increase in the directionof the second rod portion.

In particular, there is provision for the support face to be free fromsteps and/or edges and/or the like.

It is completely conceivable for the support face to have a plurality ofsequential portions in the axial direction, for example, a plurality ofconical portions with different opening angles.

It is further considered to be particularly advantageous for the supportface to be free from planar faces, that is to say, faces which areconstructed perpendicularly to a longitudinal axis of the rod whichextends in an axial direction.

It is completely conceivable for the support force to be adjoined at theradially outer side and/or radially inner side by another face of thebearing portion, wherein this additional face does not necessarily havea diameter which increases in the direction of the second rod portion.It is, for example, conceivable for an annular planar face to adjoin thesupport face at the radially inner and/or radially outer side. In placeof or in addition to planar faces or surface portions, rounded faces orradii may also be provided. It is also completely conceivable for therod seal to be in abutment with this other face or these other faces.

Preferably, the support face forms the radially innermost face, withwhich the rod seal is in abutment. The redirection of the forces in aradially outward direction thereby already begins close to the rod.

Preferably, the rod seal is supported in the direction of the second rodportion exclusively on the support face so that over the entire contactface a force redirection is carried out in a radially outward direction.However, it is completely conceivable for the rod seal to also besupported in the direction of the second rod portion on surface sectionsof the bearing portion which are not constructed in the manner of thesupport face. For example, the bearing portion could have adjacent tothe discharge structure planar surface portions which are consequentlyconstructed perpendicularly to a longitudinal axis of the rod whichextends in an axial direction.

When the rod seal is also supported on surface sections of the bearingportion which are not constructed in the manner of the support face, itis considered to be particularly advantageous for the face of the rodseal in abutment with the support face to be greater than the face ofthe rod seal in abutment with the remaining surface sections.

Preferably, a ratio of the largest diameter of the support face withrespect to the smallest diameter of the support face is from about 1.5to about 3.0.

It is considered to be particularly advantageous for the support face tobe able to be described by a rotation face which is produced by means ofrotation of a line about a rotation axis which is formed by thelongitudinal axis of the rod. Preferably, the line is a straight linewhich is inclined with respect to the longitudinal axis. The rotationsurface then corresponds to the covering face of a straight truncatedcone, wherein an opening angle of the truncated cone corresponds todouble the inclination angle of the straight line. However, the line mayabsolutely also be a curved line.

It is considered to be particularly advantageous for the support face ofthe covering face to correspond to a truncated cone with a circular baseface. Such a support face can be produced in a particularly simple andcost-effective manner.

It is further considered to be particularly advantageous for an angleformed by the support face and a longitudinal axis of the rod to be lessthan about 90°, for example, from about 60° to about 85°, in particularfrom about 70° to about 80°. These angular ranges have been found to beparticularly advantageous with respect to the most constant possiblepressing force of the sealing lips on the rod over a particularly largepressure range of the flowable medium.

It is considered to be particularly advantageous for the sealingarrangement to have a resiliently deformable clamping element, whereinthe clamping element is in circumferential abutment with a covering faceof the rod seal facing away from the rod and presses the sealing lipsagainst the rod. Preferably, the covering face surrounds the sealinglips circumferentially. Alternatively or additionally, it is alsoconceivable for the clamping element to be in abutment with the rod sealat a side of the rod seal facing away from the support face of thedischarge structure and to press the rod seal against the support faceof the discharge structure. The use of a clamping element has been foundto be advantageous with regard to a particularly good sealing action, along service-life and secure support of the rod seal in the housing, forexample, the bearing portion. In particular, the assembly can also becarried out in a particularly simple manner, for example, the rod sealcan first be introduced into the bearing portion of the housing andsubsequently be fixed to the clamping element in the bearing portion.

In connection with a clamping element, it is considered to beparticularly advantageous when the clamping element is supported in abearing pocket formed by the bearing portion and/or by the rod seal, inparticular a part-region of the bearing portion to engage behind theclamping element at a side facing the first rod portion and consequentlya side facing the cavity.

The bearing pocket is preferably constructed to be open in the directionof the cavity. The assembly and disassembly of the rod seal are therebyfacilitated.

The clamping element is preferably supported at the radial outer side onthe bearing portion.

It is considered to be particularly advantageous for the rod seal to beconstructed in one piece.

In particular, the rod seal comprises a single material. In this regard,the rod seal is free from additional material components, such as, forexample, a reinforcement ring, as provided, for example, in radial shaftsealing rings. The single material may absolutely be a mixture of twodifferent elastomer materials with different hardnesses.

However, it is also completely conceivable for the rod seal to haveregions which comprise different materials, in particular differentelastomer materials with different hardnesses.

It is considered to be particularly advantageous with regard to a mosthomogeneous possible pressing pressure of the first sealing lip and thesecond sealing lip against the rod seal for the covering face of the rodseal, with which the clamping element is in abutment, in an initialstate of the rod seal, consequently in a non-deformed state, to have adiameter which increases in the direction of the first rod portion. Thecovering face in the initial state of the rod seal is thus configured insuch a manner that it tapers in the direction of the second rod portion.Preferably, the covering face of the rod seal corresponds to thecovering face of a truncated cone having a circular base face. It isconsidered to be particularly advantageous for an angle formed by thecovering face of the rod seal and the longitudinal axis of the rod to befrom about 2° to about 15°, in particular from about 3° to about 8°, ina particularly preferred manner from about 4° to about 6°. Such aconfiguration promotes a deformation of the rod seal when the clampingelement is used in such a manner that at least a minimal pressing forceof the sealing lips is achieved at particularly low pressures of theflowable medium so that the sealing action is also sufficient at lowpressures of the flowable medium and nonetheless the pressing forces donot become too high at high pressures of the flowable medium.

It is considered to be advantageous for the material of the clampingelement to have a lower Shore hardness than a material of the rod seal.The use of a lower Shore hardness for the clamping element and a higherShore hardness for the seal produces in the combination the mostconsistent possible pressing force of the sealing lips against the rodseal over a large pressure range of the flowable medium. In addition,this combination has been found to be particularly advantageous withregard to low wear of the rod seal. It is assumed that a clampingelement with a lower Shore hardness can absorb the forces which aredischarged radially outwards at the support face particularly well bymeans of deformation and in this manner contributes to a small change ofthe pressing forces of the sealing lips over a large pressure range ofthe flowable medium.

It is considered to be particularly advantageous for the clampingelement to be in the form of a sealing ring. The sealing ring ispreferably in sealing abutment with the bearing portion at the radiallyouter side and in sealing abutment with the rod seal at the radiallyinner side. The use of a sealing ring has the advantage that, on the onehand, a sealing action to prevent the penetration of the flowable mediuminto the region between the clamping element and the rod seal isprevented. A penetration of flowable medium into this region is moredisadvantageous particularly when the flowable medium is a medium whichis subjected to an ageing process or even a hardening process, as is thecase, for example, with melt adhesive. Hardened medium could, forexample, have a negative effect on the resilience or the deformabilityof the rod seal, particularly when melt adhesive hardens in the bearingpocket since the volume of the bearing pocket is then no longercompletely available for the deformation of the rod seal.

Preferably, the sealing ring has four projections in cross section. Thesealing ring is in particular in the form of an X-ring or a quad ring.

It is considered to be particularly advantageous for the clampingelement to have two radially inwardly protruding projections, whereinthe sealing ring is arranged in such a manner that one projection actson the first sealing lip in such a manner that the first sealing lip ispressed against the rod and the other projection acts on the secondsealing lip in such a manner that the second sealing lip is pressedagainst the rod. A particularly good and homogeneous sealing action anda particularly constant pressing force of the sealing lips is thusensured over a large pressure range of the flowable medium.

It is considered to be particularly advantageous for the clampingelement to contact the bearing portion directly at the radially outerside.

It is further considered to be particularly advantageous for a hollowspace which is open in the direction of the cavity to be formed betweenthe rod seal and the bearing portion or for the rod seal to have ahollow space which is open in the direction of the cavity, wherein theclamping element, in particular the sealing ring, seals this hollowspace with respect to the cavity, in particular the clamping elementfills this hollow space. The hollow space may in particular form thebearing pocket or a part-region of the bearing pocket.

It is considered to be particularly advantageous for an abutmentportion, which is in abutment with the support face, of the rod seal toprotrude radially outwards with respect to a sealing portion of the rodseal, which sealing portion has the sealing lips and is adjacent in theaxial direction.

A ratio of a maximum outer diameter of the abutment portion with respectto a maximum outer diameter of the sealing portion is preferably fromabout 1.2 to about 2.

With regard to the bearing portion, it is considered to be particularlyadvantageous for the bearing portion to be a component of a bearingsleeve which is releasably connected to the remaining housing, whereinthe rod extends through the bearing sleeve.

Preferably, the sealing ring and/or the rod seal comprise an elastomermaterial, preferably different elastomer materials.

Preferably, a material of the rod seal has a hardness of from about 50Shore D to about 65 Shore D and/or a material of the clamping elementhas a hardness of from about 60 Shore A to about 80 Shore A.

A travel path of the rod, for example, from the first end position intothe second end position, is preferably at least about 0.2 mm, inparticular from about 0.2 mm to about 2 mm, in a particularly preferredmanner from about 0.3 mm to about 0.5 mm.

A diameter of the rod is preferably from about 1 mm to about 12 mm, inparticular from about 2.5 mm to about 6 mm.

The material of the rod seal is in particular PTFE, filled PTFE orfluoropolymers. The material of the clamping element is in particularfluorinated rubber, preferably fluorocarbon rubber (FKM).

The rod seal according to the invention has a center axis which extendsin an axial direction and at least two radially inwardly directedsealing lips which are spaced apart from each other in the axialdirection and which circumferentially surround the center axis, whereinthe rod seal has two ends which are opposite each other in the axialdirection, wherein one end of the two ends has an end face whichcircumferentially surrounds the center axis for end-side support of therod seal on an external support face, wherein the end face has adiameter which decreases in the direction of the other end of the twoends. The end face thus tapers in a funnel-like manner in the directionof the other end.

The external support face may, for example, be the support face of thedischarge structure.

The external support face may in particular be a support face which isinclined in the direction towards the center axis.

The end face preferably corresponds to the covering face of a truncatedcone having a circular base face. In particular, an angle definedbetween the cone axis and a surface line of the cone is from about 60°to about 85°.

It has been found to be particularly advantageous for the end face tomerge into the second sealing lip.

Preferably, the rod seal has at a side facing away from the center axis,consequently radially outwards, a covering face which circumferentiallysurrounds the center axis, wherein the covering face has a diameterwhich increases in the direction towards the other end. The coveringface thus tapers in the direction of one end.

Preferably, the second sealing lip is formed in the axial directionbetween the first sealing lip and the end face.

Preferably, the end face and the covering face of the rod seal areformed to be spaced apart from each other in the axial direction andconsequently do not overlap. Preferably, the second sealing lip isformed in the axial direction between the covering face of the rod sealand the end face of the rod seal. This has been found to be particularlyadvantageous with regard to the sealing action with different mediumpressures.

It is considered to be advantageous for an angle enclosed by the endface and the center axis to be from about 60° to about 85°, inparticular from about 70° to about 80°, and/or for an angle enclosed bythe covering face and the center axis to be from about 2° to about 15°,in particular from about 3° to about 8°, in a particularly preferredmanner from about 4° to about 6°.

Preferably the rod seal has recesses, in particular for receiving theprojections of the clamping element. In particular, the abutment portionhas two recesses which circumferentially surround the center axis forreceiving a protruding projection, which circumferentially surrounds therod in each case, of the clamping element.

It is considered to be particularly advantageous for the rod seal and/orthe bearing portion and/or the support face of the discharge structureand/or the end face of the rod seal and/or the covering face of the rodseal to be formed in a rotationally symmetrical manner with respect tothe longitudinal axis of the rod or the center axis of the rod seal.

It is further considered to be particularly advantageous if, in aninitial state of the rod seal, consequently in a state in which the rodseal is not supported in the bearing portion, a ratio between a firstinner diameter in the region of the first sealing lip and a second innerdiameter in the region of the second sealing lip to be from about 0.9 toabout 1.1, preferably about 1.0.

Preferably, the sealing lips have different geometries.

The statements relating to the sealing arrangement according to theinvention and the advantageous embodiments thereof apply accordingly tothe output apparatus and the rod seal. The statements relating to theoutput apparatus according to the invention and the advantageousembodiments thereof apply accordingly to the sealing arrangement and therod seal. The statements relating to the rod seal according to theinvention and the advantageous embodiments thereof apply accordingly tothe sealing arrangement and the output apparatus.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

In the accompanying drawing figures, the invention is illustrated ingreater detail with reference to one or more exemplary embodimentswithout being limited thereto.

FIG. 1 shows a sectioned view of an exemplary embodiment of an outputapparatus with a sealing arrangement according to the invention.

FIG. 2 a shows a sectioned view of the sealing arrangement of the outputapparatus according to FIG. 1 .

FIG. 2 b shows a part-region of FIG. 2 a in an enlarged illustration.

FIG. 3 shows a component of the sealing arrangement according to FIG. 2a , in particular, a rod seal as a perspective view.

FIG. 4 shows the rod seal according to FIG. 3 as a sectioned view.

FIG. 5 shows a component of the sealing arrangement according to FIG. 2a , in particular, a bearing sleeve, as a sectioned view.

FIG. 6 shows a graph relating to a development of the cumulative lipforce in the region of the respective sealing lip as the pressure of theflowable medium increases in a sealing arrangement according to FIG. 7 .

FIG. 7 shows the sealing arrangement relating to the graph in FIG. 6 .

FIG. 8 shows a graph relating to a development of the cumulative lipforce in the region of the respective sealing lip as the pressure of theflowable medium increases in a sealing arrangement according to FIG. 9 .

FIG. 9 shows the sealing arrangement relating to the graph in FIG. 8 .

FIG. 10 shows a part-region of FIG. 1 as an enlarged illustration.

FIG. 11 shows a graph relating to a diameter of a support face of adischarge structure in accordance with the axial position.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows an output apparatus 1 for discharging a flowable medium, inthis instance an adhesive output apparatus, having an embodiment of thesealing arrangement according to the invention. The sealing arrangementper se is illustrated in greater detail in FIG. 2 a and FIG. 10 .

The output apparatus 1 serves to intermittently discharge the adhesiveat a switching frequency of up to about 150 Hz. The output apparatus 1has a housing 9, 10 having a cavity 2 for receiving the flowable medium.The housing 9, 10 has a first housing portion 10 and a second housingportion 9 in the form of a bearing sleeve, wherein the cavity 2 forreceiving the flowable medium is formed between the housing portion 10and the housing portion 9. A discharge opening 4 which opens into thecavity 2 for discharging the flowable medium is formed in the housingportion 10. The discharge opening 4 serves to apply the flowable mediumto a substrate, which is not illustrated. The housing portion 9 isreleasably connected to the housing portion 10, in this instance screwedto the housing portion 10. Between the housing portion 9 and the housingportion 10, a static seal, in this instance a sealing ring 3, isarranged in order to seal the cavity 2 in the region between the twohousing portions 9, 10.

The output apparatus 1 has a rod 5, wherein the rod 5 is supported inthe housing 9, 10 so as to be able to be moved between a first endposition and a second end position in the axial direction X along alongitudinal axis 17 of the rod 5, and vice versa, wherein the rod 5extends through the second housing portion 9 which is in the form of abearing sleeve in the axial direction X. The movement of the rod 5 isindicated by the double-headed arrow 30 in FIG. 1 . A first rod portion5 a of the rod 5 is arranged at a side of the second housing portion 9facing the cavity 2 and a second portion 5 b of the rod 5 is arranged ata side of the second housing portion 9 facing away from the cavity 2.Depending on the position of the rod 5, a differently sized proportionof the rod 5 is arranged at the respective side of the second housingportion 9. The first rod portion 5 a has a sealing portion 6, whereinthe sealing portion 6 in the first end position closes the dischargeopening 4 at a side facing away from the cavity 2. In the second endposition, the sealing portion 6 is arranged to be spaced apart from thedischarge opening 4. Since the flowable medium located in the cavity 2is under a higher pressure than the environment, flowable medium flowsout of the discharge opening 4 in the second end position. Consequently,the flowable medium is discharged in the second end position of the rod5. In this instance, the switching is carried out at a relatively highswitching frequency in the range from about 1 Hz up to about 150 Hz,wherein the switching frequency relates to the time interval of twosuccessive first end positions. Consequently, a switching frequency ofabout 1 Hz corresponds to an adhesive application which lasts for about1 second. At higher switching frequencies, the duration of therespective adhesive application is accordingly shortened. It iscompletely conceivable for the time interval between two successiveadhesive applications to be several seconds. This may, for example, benecessary when several substrates are conveyed one after the other on aconveyor belt past the discharge opening in order to apply the flowablemedium thereto. The output apparatus 1 is in this instance generallytimed in such a manner that flowable medium is discharged only when asubstrate is located in the application region of the discharge opening.FIG. 1 shows the rod 5 in the first end position.

The output apparatus 1 has a pneumatic drive 8 having a drive housing 23which is connected to the first housing portion 10, wherein the rod 5protrudes with the second rod portion 5 b into the drive housing 23. Thedrive 8 is operationally connected to the second rod portion 5 b of therod 5 in order to move the rod 5 from the first end position into thesecond end position, and vice versa. In this instance, a piston 24,which can be acted on with compressed air, of the drive 8 is connectedin the region of a free end of the second rod portion 5 b to the secondrod portion 5 b.

In a bearing portion 9 which in this instance is formed by the secondhousing portion 9 in the form of a bearing sleeve, a rod seal 7 issupported in a fixed manner, wherein the rod 5 extends through the rodseal 7 in the axial direction X. The rod 5 moves relative to the housing9, 10 so that the rod seal 7 forms a dynamic seal. The rod seal 7 has asealing portion 11 which circumferentially surrounds the rod 5 and whichhas a first sealing lip 12 and a second sealing lip 13. The firstsealing lip 12 is in this instance formed between the cavity 2 and thesecond sealing lip 13. Accordingly, the sealing lips 12, 13 are spacedapart from each other in the axial direction X. The two sealing lips 12,13 contact the rod 5 circumferentially. The rod 5 moves during itstranslational movement relative to the sealing lips 12, 13.

The bearing portion 9 has a discharge structure 29 which protrudes inthe direction of the cavity 2, wherein the discharge structure 29 has asupport face 15, consequently a surface which circumferentiallysurrounds the rod 5 and which is formed on an outer side of thedischarge structure 29 which faces away from the rod 5. The rod seal 7further has an abutment portion 14 which circumferentially surrounds therod 5 for axially supporting the rod seal 7 on the support face 15 ofthe discharge structure 29 which circumferentially surrounds the rod 5.The support face 15 is in this instance configured in such a manner thatforces acting in an axial direction X on the support face 15, as presentas a result of the pressurised medium, are discharged radially outwards.To this end, the support face 15 has a diameter Da (see FIG. 11 ) whichincreases in the direction of the second rod portion 5 b, consequentlycounter to the axial direction X, in particular, in a negative Xdirection. In specific terms, the support face 15 is constructed in sucha manner that the support face 15 corresponds to the covering face of alinear truncated cone which has a circular base face and whose tip facesin the direction of the first rod portion 5 a. The support face 15 isconsequently a face which tapers conically in the direction of thecavity 2. An angle α enclosed by the support face 15 and thelongitudinal axis 17 of the rod 5 is in this instance about 75°.Accordingly, an opening angle of the truncated cone is about 150°. Thedevelopment of the diameter Da depending on the position in the axialdirection X is schematically shown in FIG. 11 . The diameter Dadecreases as the X value increases from a maximum value Dα^(max) in alinear manner to a minimum value Dα^(min). Accordingly, the diameter Daof the support face 15 increases in the direction of the second rodportion 5 b. A ratio of Dα^(max) to Dα^(min) is in this instanceapproximately 2.2.

The rod seal 7 is in this instance retained so as to be fixed inposition in the bearing portion 9 by means of a resiliently deformableclamping element 16 which is in the form of a quad ring 16. The quadring 16 is circumferentially in abutment at a radially outwardly facingcovering face 18, which faces away from the rod 5, of the sealingportion 11 with the sealing portion 11 and the sealing lips 12, 13 beingpressed by means of projections 20 of the quad ring 16 onto the rod 5,as can be seen in particular in FIG. 2 b . The quad ring 16 isadditionally in abutment at a side facing away from the support face 15with the abutment portion 14 of the rod seal 7, wherein the quad ring 16presses the abutment portion 14 against the support face 15 of thedischarge structure 29. As can be seen in particular in FIG. 5 , thequad ring 16 is supported in a bearing pocket 25 which is formed betweenthe bearing portion 9 and the rod seal 7, wherein this bearing pocket 25is constructed to be open in the direction of the cavity 2. Apart-region of the bearing portion 9 forms an undercut 26, wherein thisundercut 26 engages behind the quad ring 16 at a side facing the cavity2 and consequently fixes it in the axial direction X. The quad ring 16completely fills this bearing pocket 25 which forms a hollow space inthe installed state. Flowable medium is thereby prevented from enteringthis hollow space and consequently between the clamping element 16 whichis in the form of a sealing ring, and in particular, a quad ring, andthe rod seal 7. The clamping element 16 which is in the form of asealing ring consequently performs two functions, in particular, thefunction of pressing the sealing lips 12, 13 against the rod 5 and thefunction of a static seal between the bearing portion 9 and the rod seal7.

The sealing ring 16 has both in the axial dimension thereof and in theradial dimension thereof with respect to the dimensions of the bearingpocket 25 an excess dimension so that in the assembled state the sealingring 16 is joined in the annular bearing pocket 25 with a press fit.

The rod seal 7 per se is best illustrated in FIG. 3 and FIG. 4 in aninitial state, consequently a non-deformed state. The rod seal 7 isformed in a rotationally symmetrical manner with respect to a centeraxis 19 of the rod seal 7. An end face 21 which in the installed statemoves into abutment with the support face 15 of the discharge structure29 has a diameter D_(γ) which decreases in the direction of the otherend 28 of the two ends 27, 28. The end face 21 encloses with the centeraxis 19 of the rod seal 7 an angle γ which in this instance is about 75°and is consequently of the same size as the angle α. The end face 21 ofthe rod seal 7 and the support face 15 of the discharge structure 29 canin this instance be described by the covering face of the same truncatedcone, wherein a surface normal of the end face 21 of the rod seal 7faces radially inwards and a surface normal of the support face 15 ofthe discharge structure 29 faces radially outwards.

The rod seal 7 per se is configured in such a manner that the coveringface 18 of the sealing portion 11 has a cross section which expands inthe axial direction X in the direction of the first rod portion 5 a andconsequently in the direction of the cavity 2, wherein the covering face18 corresponds to the covering face of a truncated cone which has acircular base face and whose tip faces in the direction of the secondrod portion 5 b. Accordingly, a diameter Dβ of the covering face 18increases in the direction of the other end 28. An angle β enclosed bythe covering face 18 of the rod seal 7 and the center axis 19 of the rodseal 7 is in this instance about 5°. When the rod seal 7 is installed inthe sealing arrangement, the sealing ring 16 acts on the covering face18 of the rod seal 7 and, with the covering face 18 of the rod seal 7being deformed, presses the sealing lips 12, 13 against the rod 5.

As can be seen in particular in FIG. 4 , the covering face 18 of the rodseal 7 and the end face 21 of the rod seal 7 are spaced apart from eachother in the axial direction X and consequently do not overlap. In theaxial direction X, the second sealing lip 13 is formed between thecovering face 18 of the rod seal 7 and the end face 21 of the rod seal7.

A ratio between a first inner diameter D1 in the region of the firstsealing lip 12 and a second inner diameter D2 in the region of thesecond sealing lip 13 is in this instance about 1.0. The inner diametersD1 and D2 are in this instance slightly smaller than the diameter of therod 5.

In the region of the abutment portion 14, the rod seal 7 has recesses 22which are formed at the side of the abutment portion 14 facing away fromthe end face 21 and which circumferentially surround the center axis 19,wherein these recesses 22 serve to receive circumferential projections20 (see FIG. 2 b ) of the quad ring 16.

The advantages of the sealing arrangement according to the invention, inparticular the conical support face 15 or conical end face 21, becomesclear from a comparison of the graphs illustrated in FIG. 6 and FIG. 8 .

FIG. 6 relates in this instance to a sealing arrangement which incontrast to the solution according to the invention does not have aconical support face, on which the rod seal 7 is supported, but insteadhas a planar support face for the rod seal 7. The enclosed angle α isaccordingly about 90°. The clamping element 16 is furthermore not a quadring, but instead an annular pretensioning spring made of metal with aradially inner leg and a radially outer leg, which are connected to eachother at the end. The corresponding sealing arrangement is shownschematically in FIG. 7 . The graph of FIG. 6 shows the numericallytotaled pressing force in the region of the first sealing lip 12(indicated by “lip 1”), wherein the first sealing lip 12 is located inthe axial direction X at the position of approximately 3.0. Furthermore,the graph of FIG. 6 shows the numerically totaled pressing force in theregion of the second sealing lip 13 (indicated by “lip 2”), wherein thesecond sealing lip 13 is located in the axial direction X at theposition of approximately 1.0. It can be seen from the graph of FIG. 6that, as the pressure of the flowable medium increases, in this instance0 bar (“without pressure”), 10 bar and 40 bar above ambient pressurewhich is approximately 1 bar, the pressing force of the two sealing lips12, 13 on the rod 5 significantly increases. The values for the pressingforce are standardised to the pressing force of the second sealing lip13 at a medium pressure of 40 bar. In addition, the pressing force inthe region of the first sealing lip 12 and the pressing force in theregion of the second sealing lip 13 develop in substantially differentmanners. For example, the pressing force is in the region of the secondsealing lip 13 at small medium pressures less than the pressing force inthe region of the first sealing lip 12, whereas, at higher mediumpressures, the pressing force in the region of the second sealing lip 13exceeds the pressing force in the region of the first sealing lip 12. Atlow medium pressures, the pressing forces for both sealing lips 12, 13are relatively low. They are with a pressure-free medium, consequently amedium whose pressure is not increased with respect to the ambientpressure, in the region of approximately 0.1 or 0.35. Over the pressurerange from 0 bar to 40 bar which has been examined, the pressing forceschange in the region of the second sealing lip 13 relatively powerfully,in particular, by a factor of 10.

The graph of FIG. 8 relates to a sealing arrangement according to theinvention according to FIG. 9 . The values for the pressing force are inturn standardised to the pressing force of the second sealing lip 13 ata medium pressure of 40 bar. The absolute value of the pressing force ofthe second sealing lip 13 (indicated by “lip 2”) at a medium pressure of40 bar in the arrangement according to FIG. 9 is approximately identicalto the absolute value of the pressing force of the second sealing lip 13(indicated by “lip 2”) at a medium pressure of 40 bar in the arrangementaccording to FIG. 7 . The pressing forces of the first and secondsealing lip 12, 13 (indicated by “lip 1” and “lip 2”) increase in thearrangement according to FIG. 9 in a similar manner as the mediumpressure increases. In addition, even with relatively low mediumpressure, a sufficiently high pressing force is ensured between the rod5 and the first sealing lip 12 and the second sealing lip 13. This is at0 bar medium pressure in the region of 0.6 or 0.8.

The solution according to the invention consequently affords theadvantage that the pressing force between the rod 5 and the firstsealing lip 12 and the second sealing lip 13 is also sufficient at lowpressures to prevent a leakage and/or a tipping of the sealing lips 12,13 and at the same time as the medium pressure increases the pressingforce between the first sealing lip 12 or the second sealing lip 13 andthe rod 5 does not increase excessively and also does not increase in anon-homogeneous manner. Excessively powerful wear of the rod seal 7 inthe region of the sealing lips 12, 13 as a result of an excessively highpressing force is thereby prevented. Over the pressure range of from 0bar to 40 bar which has been examined, the pressing forces in thesolution according to the invention change in the region of the secondsealing lip 13 relatively little, that is to say, only in the range fromapproximately 0.6 to approximately 1.0, whereas with the solutionaccording to FIG. 7 the pressing force in the region of the secondsealing lip 13 changes from about 0.1 to about 1.0.

The quad ring 16 ensures as a pretensioning element that already in thepressure-free state or at low medium pressures a uniform pretensioningof both sealing lips 12, 13 is ensured. Furthermore, the quad ring 16prevents flowable medium from reaching the region of the abutmentportion 14 and consequently acting on the abutment portion 14, wherebythe dependency of the sealing action of the rod seal 7 on the mediumpressure applied is further reduced.

1-15. (canceled)
 16. A sealing arrangement for an output apparatus for discharging a flowable medium, the sealing arrangement having a rod seal for sealing a cavity formed in a housing and configured to receive the flowable medium in the region of a rod, wherein the rod is movably supported in the housing to be displaced in an axial direction of the rod, wherein the housing has a bearing portion, wherein the rod seal is supported in a fixed manner in the bearing portion, wherein the rod extends through the bearing portion and the rod seal so that a first rod portion of the rod and a second rod portion of the rod are arranged at different sides of the bearing portion, wherein the first rod portion is located at a side of the bearing portion facing the cavity and wherein the second rod portion is located at a side of the bearing portion facing away from the cavity, wherein the rod seal is arranged at the side of the bearing portion facing the cavity, wherein the rod seal has a first sealing lip and a second sealing lip, wherein the first sealing lip and the second sealing lip are spaced apart from each other in the axial direction, wherein the first sealing lip and the second sealing lip circumferentially contact the rod, wherein the bearing portion has at a side thereof facing the cavity a discharge structure having a support face which circumferentially surrounds the rod, wherein the rod seal is in abutment with the support face, and wherein a diameter of the support face increases in the direction of the second rod portion.
 17. The sealing arrangement according to claim 1, wherein an angle enclosed by the support face and a longitudinal axis of the rod which extends in the axial direction is from about 60° to about 85°.
 18. The sealing arrangement according to claim 1, wherein the support face corresponds to the covering face of a truncated cone having a circular base face, and wherein an angle between a surface line of the truncated cone and a cone axis of the truncated cone is from about 60° to about 85°.
 19. The sealing arrangement according to claim 1, having a resiliently deformable clamping element, wherein the clamping element is in circumferential abutment with the rod seal on a covering face of the rod seal facing away from the rod and presses the first sealing lip and the second sealing lip against the rod, and/or wherein the clamping element is in abutment with the rod seal at a side of the rod seal facing away from the support face of the discharge structure and presses an abutment portion of the rod seal formed between the support face of the discharge structure and the clamping element against the support face of the discharge structure.
 20. The sealing arrangement according to claim 1, wherein the support face of the discharge structure is described by a rotation face which is produced by means of rotation of a line about a rotation axis formed by a longitudinal axis of the rod.
 21. The sealing arrangement according to claim 19, wherein the clamping element is supported in a bearing pocket formed by the bearing portion and/or by the rod seal, and wherein a part-region of the bearing portion engages behind the clamping element at a side facing the first rod portion.
 22. The sealing arrangement according to claim 19, wherein a material of the clamping element has a lower Shore hardness than a material of the rod seal, and wherein the material of the rod seal has a hardness of from about 50 Shore D to about 65 Shore D and/or the material of the clamping element has a hardness of from about 60 Shore A to about 80 Shore A.
 23. The sealing arrangement according to claim 19, wherein the clamping element is in the form of a sealing ring having in cross section four projections in the form of an X ring or a quad ring.
 24. The sealing arrangement according to claim 19, wherein the clamping element has two radially inwardly protruding projections, and wherein the clamping element is arranged such that one projection of the two radially inwardly protruding projections acts on the first sealing lip such that the first sealing lip is pressed against the rod and the other projection of the two radially inwardly protruding projections acts on the second sealing lip such that the second sealing lip is pressed against the rod.
 25. The sealing arrangement according to claim 19, wherein the clamping element contacts the bearing portion at a radially outer side.
 26. The sealing arrangement according to claim 19, wherein a hollow space which is open in the direction of the cavity is formed between the rod seal and the bearing portion or alternatively wherein the rod seal has a hollow space which is open in the direction of the cavity, and wherein the clamping element seals the hollow space with respect to the cavity.
 27. An output apparatus for discharging a flowable medium having the sealing arrangement according to claim 1, wherein the output apparatus has a discharge opening which opens in the cavity for discharging the flowable medium from the cavity, wherein the rod is supported in the housing so as to be movable between a first end position and a second end position in the axial direction, wherein the rod has a sealing portion, wherein the sealing portion closes the discharge opening in the first end position and is spaced apart from the discharge opening in the second end position, and wherein the output apparatus has a drive operationally connected to the second rod portion of the rod to move the rod between the first end position and the second end position.
 28. A rod seal for use in the sealing arrangement according to claim 1, wherein the rod seal has a center axis which extends in the axial direction, wherein at least two radially inwardly directed sealing lips of the first sealing lip and the second sealing lip are spaced apart from each other in the axial direction and circumferentially surround the center axis, wherein the rod seal has two ends which are opposite each other in the axial direction, wherein an end-side abutment portion of the rod seal has an end face which circumferentially surrounds the center axis for an end-side support of the rod seal on the support face, and wherein a diameter of the end face decreases in the direction of one end of the two ends.
 29. The rod seal according to claim 28, wherein the rod seal at a side facing away from the center axis has a covering face which circumferentially surrounds the center axis, wherein a diameter of the covering face increases in the direction of the other end of the two ends, and wherein the covering face corresponds to the covering face of a truncated cone with a circular base face.
 30. The rod seal according to claim 28, wherein an angle enclosed by the end face and the center axis of the rod seal is from about 60° to about 85° and/or an angle enclosed by the covering face and the center axis of the rod seal is from about 2° to about 15°. 